1. Field of the Invention
The present invention relates to a touch display, especially to a touch display having a front light module, which is capable of improving the efficiency in guiding light downward, enhancing the pixel display intensity, and increasing the color saturation when used in color display applications.
2. Description of the Related Art
In the implementation of transflective or reflective touch displays, front light modules of edge-lighting type are commonly utilized for minimizing the size of the touch displays so as to make the touch displays meet the market's form factor demand.
A typical front light module of edge-lighting type generally installs a light-guiding means on the top face of a light guide plate for guiding light downward, so as to transform an edge light to a uniform plane light, which emits light beams downward to provide illumination for a display. Please refer to FIG. 1, which illustrates a cross sectional view of a reflective type touch display using a typical front light module. As illustrated in FIG. 1, the reflective type display reflective type display includes a light source 100, a light guide plate 110, a touch panel 120, and a reflective type display 130.
In the touch display, the light source 100 is used for providing incident light.
The light guide plate 110, of which the left side face is a light entrance surface neighboring the light source 100, the bottom face is a light exit surface, and the top face has a plurality of diffusion points 111, wherein, the incident light hitting the diffusion points 111 indirectly (after going through a total reflection at the bottom face of the light guide plate 110) or directly will be scattered off, and some of the scattered light—of which the traveling direction forms with the normal of the light exit surface an angle smaller than a total reflection angle—will pass through the light exit surface to illuminate the reflective type display 130.
The touch panel 120 generally has a touch structure formed over a transparent glass substrate, and the reflective type display 130 provides a picture by reflecting the light incident thereon.
Although the diffusion points 111 have the advantage of easy implementation (can use sand-blasting process), however, the efficiency in guiding light downward is not good enough—some of the light scattered by the diffusion points 111 will emit away from the top face of the light guide plate 110, causing energy loss.
To improve the efficiency in guiding light downward, there is another typical design using microstructure as a means for guiding light downward. Please refer to FIG. 2, which illustrates a cross sectional view of a reflective type touch display using another typical front light module. As illustrated in FIG. 2, the reflective type touch display includes a light source 200, a light guide plate 210, a touch panel 220, and a reflective type display 230.
In the touch display, the light source 200 is used for providing incident light.
The light guide plate 210, of which the left side face is a light entrance surface neighboring the light source 200, the bottom face is a light exit surface, and the top face has a plurality of V type microstructures 211, wherein, the incident light hitting the V type microstructures 211 indirectly (after going through a total reflection at the bottom face of the light guide plate 210) or directly will be reflected to travel down along the normal of the light exit surface to pass through the light exit surface, and therefore illuminate the reflective type display 230.
The touch panel 220 generally has a touch structure formed over a transparent glass substrate, and the reflective type display 230 provides a picture by reflecting the light incident thereon.
Although the V type microstructures 211 can provide better efficiency in guiding light downward, nevertheless, they have the disadvantage of being not easy to implement.
What is more, as the diffusion points 111 of the front light module of FIG. 1 and the V type microstructures 211 of the front light module of FIG. 2 are located at the top face of the light guide plate, therefore they both have the problems of interfering with a user's viewing the display and being subject to getting scratched.
In view of the foregoing problems, the present invention proposes a touch display having a novel structure.